Mycoplasma & Ureaplasma

The smallest free-living bacteria. No cell wall. – Consequently, they stain poorly and are resistant to penicillin and other antibacterial drugs that target the cell wall. Their cell membranes contain sterols, which is unique. They are facultative anaerobes – except for Mycoplasma pneumoniae, which is a strict aerobe. When cultured, they grow slowly, and have a fried-egg appearance. Aka, "Eaton agent." Causes a range respiratory infections, from mild cases of tracheobronchitis to severe cases of atypical pneumonia. Infection spreads slowly among individuals living in close contact, such as families. Some people will be asymptomatic. Long incubation period, and infection can persist for months. Post-infection, acquired immunity tends to be short-lived and incomplete. Diagnostic tests include PCR amplification and ELISA. Treatment: erythromycin, doxycycline, or fluoroquinolones; be aware that macrolide-resistant strains are a growing concern. Transmission of the bacteria occurs via respiratory droplets. Primary site of infection is the respiratory tract. Mycoplasma pneumonia has an attachment organelle that facilitates motility and adherence to these cells; P1 adhesins are key in this process. After attachment, the bacteria destroy the ciliated cells, which inhibits microbial clearance from the respiratory tract. – Cellular destruction is achieved via production of hydrogen peroxide and Community Acquired Respiratory Distress Syndrome exotoxin (CARDS). The bacteria acts as superantigens: they recruit and activate inflammatory cells, leading to the release of cytokines; inflammatory cells and their products are responsible for many of the clinical manifestations of infection. Treated with corticosteroids or immunoglobulins; patients with thrombosis should be given anticoagulants. These infections are the result of inflammatory cytokines, autoimmunity, and the formation of immune complexes. Individuals may experience neurological or cardiac diseases, thrombosis, hemolytic anemia, arthritis, or cutaneous/mucosal lesions such as Stevens-Johnson Syndrome. – Be aware that these issues may arise in the presence or absence of atypical pneumonia. Primarily affect the urogenital tract. Bacteria are transmitted via sexual activity (contact with infected mucosal surfaces). Mycoplasma genitalium Infection is often asymptomatic. It is a common cause of non-gonococcal urethritis in men. Associated with cervicitis, pelvic inflammatory disease, and adverse pregnancy outcomes in women. Treat with: azithromycin or moxifloxacin. Mycoplasma hominis and Ureaplasma urealyticum Common colonizers of the female reproductive tract. Mycoplasma hominis is associated with postpartum fever and pyelonephritis. Treat with clindamycin. Ureaplasma urealyticum is associated with urethritis, pyelonephritis, and adverse pregnancy outcomes. Treated with Erythromycin. Ureaplasma urealyticum produces urease, which differentiates it from the Mycoplasmas. Vertical Transmission & Neonatal Infection Both Mycoplasma hominis and Ureaplasma urealyticum can be vertically transmitted from mother to fetus; In the neonate, these bacteria are associated with pulmonary disease, bacteremia, and meningitis; treatment of infected mothers may prevent transmission and neonatal disease.